Question for Flex 6300 owners

FLEX SAYS: "The FLEX-6300, FLEX-6500 and FLEX-6700 all have the option of receiving from the XVTR port. The XVTR port is not recommended as a receive antenna port if an
external preamp is used on its antenna. Transmission on the XVTR port could put
up to +10 dBm of reverse power into the connected preamp."

Many people I know, including myself, use a variety of preamps as needed on their extensive receive antennas. My Hi-Z array has 8 preamps with one at each 24ft tall rx antenna and I have another two available inside the shack as well as the DXE preamp at the array center (over 800ft away). Isnt there a way to inhibit the TX side of that same bnc connector so up to +10dbm of power doesn't fry the preamps? I know I am ok with the 6700 as I have dedicated RX inputs but what about the users of a 6300? I sent my 6700 in for a tuneup so currently I cant open the GUI to check if indeed the Xvtr port can be inhibited from TX only. (and of course I cant remember) .

Lots of 6XXX users are using the xvtr port for their Hi-Z or other preamped low band rx antennas so PLEASE idiot-proof this port from inadvertent transmitting. A checkbox to permanently disable TX would be most welcome in a future update.

Before we go add this, I'd like to understand if the devices you are concerned about would even be damaged with 10mW of power. My guess is that they would not be. This is 2 volts peak-to-peak of RF energy. If you have a device that would croak with 10mW of power, I'd like to know what it is and what it's limits are.

Steve, hope you are well. Love my 6300 and Maestro. I have now replaced two preamps on my Pixel (now DX Eng Mag Loop Antenna). I am looking at a hardware solution to protect the feed line to the magloop RX on TX. Currently I have the RX ant on ANT2. It would be amazing if would could implement the TX Inhibit on any of the ANTn. I liked your argument .. but .. it would be much easier if this was just implemented in software. I think you told me a year or so back ... it was now on the list. I assume there is a not a public view of your sprint backlog of features or any way of knowing we approx this may hit SmartSDR for Meastro.

On my 6300 I have a EWE and pennant connected to the XVTR port with a KD9SV rx preamp. Never an issue, there is simply nothing to worry about. Just don't set up the XVTR in the setup and you can forget about it.

Hi Jon, we are not talking about protecting the radio input from overload by using either this DXE Unit or the Array Solutions AS-FEP unit for example. We are asking about protecting the external preamps from the radio output per the F6300 manufacturers warning as stated above. Im not sure the unit you link to is intended to be used in a reverse configuration.

It may be a moot point... I have asked the RX preamp manufacturer for information as to what it will withstand for RF input on its output side.

First, during the PowerSDR era, placing an extra checkbox on a form to enable a feature for a set of users was less of a concern. But we learned that the more of these kinds of things we add, the greater number of instantaneous modes the radio could be in and the higher likelihood that the operator will get confused about the "mode" of the radio and have difficulty operating it. Our GUI designer now jokes that every time we request a checkbox option "an angel loses it's wings." It's a tongue-on-cheek expression, but the point is valid: lots of options add lots of complexity.

Second, from our perspective, the more options like this that are added, the higher the support load becomes because operators can casually check a box like this and then totally forget the box ever existed. Later when they are trying to transmit, we end up fielding a call from an upset customer that has spent several hours taking apart their station trying to find a problem, and believe their radio is broken. Although the resolution might be quick, it's no fun for our customer to have this kind of experience. This can also be embarrassing for a customer when in reality it's our fault for making something complex, really.

Third, I am a microwave guy and so my entire lash-up consists of a cascade of amplifiers, preamps, power supplies, etc. all depending on one another. Most microwaves will tell you that if you build a hardware system than can blow up if it weren't for a software setting, that what you have is a ticking time bomb. In other words, if you can break something with a setting in software, you eventually will. Knowing that your system can never achieve an over-power, over-current, over-voltage, etc. condition if you do something wrong in the operation of the station brings a certain comfort. It's nice to be able to tell a fellow ham "sure, try it out -- you're not going to hurt anything." I've operated stations before where I've been given very strict instructions that ended with "and if you do ___________ you will destroy _________ which will cost me _________." It's a lot less fun to operate given that set of conditions.

Fourth, as I suggested before, I think it is likely that this level of RF wouldn't hurt most devices anyway. In the HF world, we're all used to thinking that transmit power kills anything but antennas, amplifiers, coax and relays, but this is a very low level of power. If it's not a problem let's not fix it.

For these reasons, I'm going to resist doing something like this. But if it is shown that this is a necessary thing to do, of course we'll go do it. I'm just asking that before we complicate things for everyone, let's make sure it has to be done.

Steve, thanks for the robust and logical feedback. I'm all for employing the KISS principle where applicable.

I sent a note to Lee, K7TJR, the Hi-Z designer who warned of inserting rf into the JFET's in the preamps. I asked him to comment on the 10mW that you say is the limit of TX power that could be applied accidently.

In theory and philosophy your reply is logical but there are other aspects of this radio to consider. Certainly the more degrees of freedom you provide the more perverse permutations you will reap, and the harder the system will become to control and trouble shoot. I understand that but some things are frivolous and some add robustness to a system. Absolutely defining the nature of a port reduces your degrees of freedom when it comes to making a mistake (desirable) but it may increase the # of phone calls. Those phone calls over time also increase the robustness however because your owners become smarter, and smart satisfied owners are your best salesmen. I love discussing the things I like about my new radio with potential customers.

The way you make a transverter tx mistake is you make a wrong choice or you forget or some piece of software, even SSDR chooses for you. I have never had the radio come up in transverter mode but I have had it come up in TX and RX ant 2 on some bands quite often. I never use ant 2. There is nothing connected to ant 2. It's not hard to spot because when the panadapter is reading -140 dBm I say "OH this must be in ant 2". If it comes up in TX ant 2 then I have to trouble shoot why my SWR is 100:1. It's either some state instability in the software (like it was preceded by some kind of funky shutdown) or old Hiram Percy is playing a trick on me. Either way it makes me nervous.

Your radio's code is not exclusively developed by you (Flex). You have an API that allows others to control the radio through their own software development. The 6300 has a transverter port which doubles as a receive port. It is a major selling point of the radio. I've had some email that indicates that one point, a external rx port, makes or breaks the sale. I don't see any reason to not have the software tell that port exactly how to behave as part of the ﻿﻿API and the setup form instead of relying on fail safes. If you stuffed a cocked and loaded .45 in your pocket would you not lock the safety or would you rely on the hope that a misfire probably won't hit someone? There is a syndrome called Glock leg. It happens when someone pulls their Glock after doing a 3lb trigger job on the gun and that silly button they call a safety somehow gets defeated and you wind up shot in the ass. (this is my appeal to the Texan in you)

I've been thinking about getting one of those $500 Pixel antennas Greg uses at the hamfests. Maybe you guys could shoot some RF into that thing for me and see if it blows up.

I have received another request to do this for the ANT1/2 ports as well. I'm interested in how folks feel about adding these as switches in setup vs. not allowing it. If you have an opinion, feel free to chime in. For tracking purposes, this is being tracked as US2215.

Steve: FWIW here is the reply that Bob W9BF and I received from Lee at Hi-Z antennas about our concerns using the Transverter port for preamplified receive antennas.

Hello Bob and Larry,
I can confirm that the 10mw transmit power will likely not damage a Hi-Z 75 ohm
preamp. I cannot speak for other brands. However, the level seen inside our
amplifier is not just 2 volts peak to peak. First, our systems are 75 ohm
instead of the 50 ohms stated by N5AC which makes 2.45 volts at the output of
the amp. This then is transformed at 2:1 inside the amp which makes the voltage
at the transistor 4.9 volts peak to peak. While this will likely not cause any
damage it may cause IMD distortion in ours or other brands of amplifiers. While
you would not hear this, it would be very harmful in a multi receiver station
sharing RX antennas even on another band, and even if the receiving antenna is
simply being split and sent to another radio. My opinion is using the 10 mw
output transverter port for receiving antennas would not be a good idea in a
multi radio environment. A single radio environment should be
OK.

I second the concern expressed by a user over inadvertent TX on ANT1/ANT2. It is very easy to be operating two slices with separate antennas and transmitting on a non-resonant antenna. I've already shown that my tribander can make contacts on 6m with the throttled back power on SWR overlimit.

What would be vy fb on setup would be a per band TX permission setting for each ANT and enable/disable XVTR for TX.

Lee's, K7TJR, comments strongly suggest that transmitting 10mW could be compromising. The word "could" infers the option being discussed is worthwhile IMHO.

Would recommend the addition of transmit inhibit on ANT1, ANT2, and XVTR ports.

Method: On setup screens: Add a LOV (drop down) for each of ANT1, ANT2 and XVTR with values: TX/RX, RX, Inhibit.

Our GUI designer now jokes that every time we request a checkbox option
"an angel loses it's wings." It's a tongue-on-cheek expression, but the
point is valid: lots of options add lots of complexity. - Steve N5AC

Agreed - 100 % unless there is a strong case, see blow.

Later when they are trying to transmit, we end up fielding a call from
an upset customer that has spent several hours taking apart their
station trying to find a problem, and believe their radio is broken

Most microwaves will tell you that if you build a hardware system than
can blow up if it weren't for a software setting, that what you have is a
ticking time bomb. In other words, if you can break something with a
setting in software, you eventually will.

Understood, however - when I listened to your TAPAR presentation in Seattle on the 6000 series and the introduction of the 6300 (the reason I bought one) .. you focused on wanting to deliver a better user experience, support bringing new folks into SDR realm (and the hobby).

I just ordered a Pixel Mag Loop receive antenna, to add a fast acting relay on the feedline to protect me from myself (sending RF down the feedline by accident), it would be considerable expense effort and more infrastructure to maintain.As this is a hobby, I work in Product Development at Oracle during the day .. I am often operating with a sleep deficiency. If the contesters do come, as I suspect they will after listening to your talk - they too will be operating sleep deprived and subject to making a mistake. Switching an antenna port to no load/ant, TX on receive antenna.

If I blew the LNA on my receive antenna or the finals on my 6300 (as I had no ANT connected to a port, in error -- While it would be self inflicted, some part of me would be upset my 6300/SmartSDR and Flex Radio .. as I would know that it would have been possible to add a feature that would protect my infrastructure.

The Alt text is in the context of the control. When I tried to click on the grayed out TX control, I would get one on the two messages, right there in context -- and I would know how and why. This should offset your concern about support calls.

Excellent analysis and commentary. I, too, want to preserve my rx preamps, but I'm more irritated at ANT mix ups when switching slices during the chase of the rare one. Very difficult for me to practice self-discipline under such circumstances.

I already own a Flex1500 and a 5000a. I've just paid a lot of cash to "upgrade" to a 6300, but apparently I have no dedicated RX port for my Wellbook loop, and the transverter port doesn't work either.

Iian, the XVTR BNC is the correct port for your rx loop. To receive off your loop you must enable the XVTR by clicking on whatever is showing as your RX antenna. This produces a menu with XVTR as an option.

I am confused by all of this. I am considering a Flex 6300 in the future for vacations as I have a 6500. If I use something like a Pixel Technologies Loop Receive antenna and have it disabled during transmissions like I do with 6500 now, isn't it (the received antenna) protected?

You should not place a RX only antenna on ANT1 or ANT2 where high power RF can hit them. I verified with the Pixel loop guys some time back that 10mW would not hurt the antenna. Placing it on the XVTR port would eliminate the possibility of damage.

Did I read that right? There is a GUI designer? With all the fuss and quality criticism of the current GUI I hope he has been supplied with a new box of wax crayons so he can work on the requested improvements. Hi hi, from my hospital bed. Love to you all.

I'm stunned that this request is still open after two years. Flex has morphed from a company that asked what its customers wants, to a beast that tells its clients what's best for them. It should rename itself to "Big Mother".

For easy to detect operator errors there should be a popup to alert the operator that a choice in config is contrary to the current directed operation instead of "nothing happening". Take the case of checking a box in setup to prohibit transmitting out of the XVTR port and six months later trying to do some QRP operations and trying to figure out why no one can hear me.
I could see myself falling into this trap.

This is funny. I told someone about the new SmartSDR and that the interface was simplified; likely because it presented less chances to the user of screwing something up royally or have a 1 Delta Ten Tango style error. :)